The guys over at BlizzPlanet have a knack for finding Knaak news (I know, I know, that was bad) -- they heard about an interview with him on a certain WoW podcast, and kindly broke down what he said for those of us who don't have the time to listen in.
It sounds like he talks pretty insightfully about how he sussed out main character traits for the NPCs of the Warcraft universe -- he based what he had them do on their past actions, and he says that Blizzard has a few "lorekeepers" (we'd imagine Chris Metzen is among them) who track the history of Azeroth and its inhabitants for reference purposes. He's only played a little bit of WoW, apparently, but he pieces the rest from lore and screenshots.
And, perhaps most interesting, at the end of the interview, he says he's working on a new book called "Stormrage," which we'd assume would be about a certain Demon/Night Elf. Fans of the extended universe will certainly want to check out the interview itself.